Saving datetimes as text

Thomas Levine occurrence at
Fri Dec 7 08:41:53 PST 2012


I am going to record video, audio and electromyography (It doesn't 
matter if that
means nothing to you.) at the same time, and I want to align the 

In case you are curious, I want to figure out why wrists make that 
cracking noise
if you twist them in that weird way that you'll know about only if you 
do it.
Electromyography measures electric potential across a muscle, so it's 
sort of like
muscle activity. More here:

All of the recording devices are plugged into the same computer, so I 
think that
using clock time would less annoying than some other approaches. Thus, 
I want to
get a datetime out of the video and audio that I'm recording.

This command seems decent for recording the video and audio.

     gst-launch-0.10 v4l2src ! timeoverlay halign=right valign=top ! \
       clockoverlay time-format="%Y-%m-%d %H:%M:%S" halign=left 
valign=top ! \
       video/x-raw-yuv,width=640,height=480 ! ffmpegcolorspace ! 
theoraenc ! \
       oggmux name=mux ! filesink location="$outfile" pulsesrc ! 
audioconvert ! \
       vorbisenc ! mux.

On my computer, the video is laggy, but the audio is not, and the audio 
is more

This command displays the time as an image, so it's enough for manually 
the video/audio with the electromyography, but it would be nice if I 
could make
it more automatic. I think that getting the start and end times of the 
recording as text would be fine.

I've never written anything with gstreamer except for hacks with 
It looks like I should use a descendant of GstClock, but that's as far 
as I've
gotten. I haven't really written C before.

Can I do something like this in gst-launch or in something similarly 



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